1. Field of the Invention
This present invention is directed to blowout preventers; to blowout preventers with opposed rams; to blowout preventers with seal structure on one ram which is received and held in corresponding space in an opposing ram; and methods of their use.
2. Description of Related Art
There is a wide variety of known blowout preventers, blowout preventer rams and seals, and methods for closing rams on a pipe.
Typical blowout preventers have selectively actuatable rams. Many such rams have a ram body with a top seal and a packer or seal holder that holds a face seal. With the rams closed on a pipe, the face seals on opposing rams contact and seal against each other. Such seals can be subject to high pressures and to chemical reaction with drilling fluids which can damage the seals. Pressure applied to a blowout preventer—either in a test or in an actual blowout situation—can cause the rams to move and wobble, which in turn causes the face seals to move with respect to each other which can result in damage to the face seals.
FIG. 1 shows parts of a prior art blowout preventer which includes two ram bodies or “blocks” (one, on the left, shown in an exploded view) each with a top seal and a face seal. Each face seal is held in a seal holder (or holders).
As shown in FIGS. 2A and 2B in a prior art blowout preventer BP, plates P of a first seal holder structure of a first ram R abut plates L of a second seal holder structure of a second ram M. Also, face seal F of the first ram R abuts a face seal C of the second ram M. Face seal portions of a single face seal are in a single plane. Similar contacts occur with the face seals and seal holders of FIG. 1.
Pressure on the blowout preventer BP, indicated by the arrows P, causes the plates on both sides 5a and 5b of the blowout preventer BP to move against each other and causes the face seals to move against each other. This movement can result in damage to the face seals. Face seal portions on both sides of a pipe (on both sides 5a, 5b) can move against and damage each other.
Prior patents disclose a variety of blowout preventers, and seals for them, including, but not limited to, U.S. Pat. Nos. 2,194,256; 2,752,119; 3,946,806; 4,043,389; 4,313,496; 4,132,267; 4,437,643; 4,456,215; 4,558,842; 4,969,390; 4,492,359; 4,550,895; 4,504,037; 3,272,222; 3,744,749; 4,253,638; 4,332,367; 4,523,639; 5,011,110; 5,025,708; 5,056,418; 5,064,164; 5,400,857; 5,515,916; 5,575,452; 5,655,745; 5,918,851; 7,207,382; 7,243,713; and 7,464,765 (all said patents incorporated fully herein for all purposes.
There has long been a need, recognized by the present inventor, for a blowout preventer in which the damaging effects of pressure applied to rams and face seals are reduced or eliminated. There has long been a need, recognized by the present inventor, for a blowout preventer which effectively and efficiently deals with pressure imposed on the blowout preventer, both in testing and in an actual blowout situation, in which unwanted movement of the rams closed on a pipe, and of their face seals, is inhibited or reduced.